Altitude-reporting encoder system

ABSTRACT

An altitude reporter comprising an altimeter, electro-optical means for tracking the position of the indicator of the altimeter, an encoder for registering the position of the indicator and providing pulse group series output corresponding to such a position, and means for operatively connecting the encoder to the electro-optical tracking means. This connecting means is effective, when the indicator moves in one direction, to operate the encoder to add increments of such movement and, when the indicator moves in the opposite direction, to operate the encoder to subtract like increments of movement. The encoder and the stepper motors which drive the encoder in response to electrical signals from the electro-optical means constitute a register.

United States Patent [72] Inventor Earl W. Springer Box 22, Fail-land,Ind. 46126 [2 1] Appl. No. 23,579 [22] Filed Mar. 30, 1970 [23] Divisionof Ser. No. 739,406,

n 4, 22 enn inan [45] Patented Nov. 2, 1971 [54] ALTITUDE-REPORTINGENCODER SYSTEM Primary Examiner-Donald O. Woodiel Attorney-Hood, Gust,Irish, Lundy & Coffey ABSTRACT: An altitude reporter comprising analtimeter, electro-optical means for tracking the position of theindicator of the altimeter, an encoder for registering the position ofthe indicator and providing pulse group series output correspond ing tosuch a position, and means for operatively connecting the encoder to theelectro-optical tracking means. This connecting means is effective, whenthe indicator moves in one direction, to operate the encoder to addincrements of such movement and, when the indicator moves in theopposite direction, to operate the encoder to subtract like incrementsof movement. The encoder and the stepper motors which drive the encoderin response to electrical signals from the elcctro-optical meansconstitute a register.

PATENTED NUVZ 1971 fi z WWW ATTORNEYS and, consequently, Heretofore, tomy ALTll'll UllI lE-REPORTHNG lEN COlDlEllt SYSTEM The presentapplication is a divisional application based upon my prior copendingapplication Ser. No. 739,406 filed June 24, 1968, now patent no.3,513,708.

it is an object of my invention to provide an altitude indicating andreporting system which is extremely reliable and simple in construction,but yet which is satisfactory for the purpose intended. My system isarranged to take readings directly from a conventional aircraftaltimeter in which pilots have great confidence and to present thesereadings in a form in which they can be transmitted via a conventionaltransponder to a ground station.

Many years of research and development and testing have produced thestandard aircraft altimeter which utilizes the forces developed bybarometric pressure changes to drive indicators or pointers. Of course,these forces are very small, the altimeter is a very delicateinstrument. knowledge, no one has been able successfully to use theforces developed by the pressure-sensing means of an altimeter to driveelectrical pickoff devices such as variable resistors. The problem isthat any such pickoff device will present such a load to thepressure-sensing means that the output of the pressure-sensing meanswill be erratic. lt is for these reasons that my system is arranged totake readings from a standard altimeter without, in any way, placing aload on the pressuresensing means of the altimeter. In fact, in thepreferred embodiment of my system, a standard altimeter, which is theonly instrument technically and legally that can be used for airnavigation, can be purchased and installed therein without, in any way,being modified. That is, my preferred system includes means for trackingthe movement of the altimeter indicator through the glass cover plate ofthe altimeter.

My system may be used in connection with a transponder carried on anairplane and arranged to transmit the identity of the plane as well asother information, such as the altitude at which the plane is flying.With the advent of radar control of air traffic, a world widesystem-utilizing pulse communication from such transponders is beingplaced in service. The success of this world wide system will depend,for the most part, on the capability of most, if not all, of the flyingaircraft to transmit via a transponder the necessary information,including altitude. My system is so simple in construction that it willbe economically feasible for small aircraft owners to purchase andinstall the system in their aircraft. It will be understood, however,that my system can be provided in forms which are sufficientlysophisticated to be used in very large and expensive and complicatedaircraft systems. My system, in one or more embodiments, is ideallysuited for use with the air data computer systems presently beingproposed for use with large commercial aircraft.

My altitude indicating and reporting system will provide an output whichis in the form of a digital code suitable for automatic altitudetransmission via the authorized air traffic control radar beacon system.This code is published in REPORT No. 8893-SP-1, for FEDERAL AVIATIONAUTHORITY CONTRACT FAA/BRD-329 Task No. 6. Further, my code complieswith the international Civil Aviation Organization (ICAO) internationalagreements. My preferred system comprises an encoder which is driven toproduce this digital code output which is suitable for transmission viaa transponder to a ground station.

My system utilizes an encoder to provide the various pulse group seriesoutputs representing 100 foot increments of altitude, the encoderincluding at least one disc having a plurality of concentrically arcuatecontact strips formed thereon, a contact member arranged to engage eachof the contact strips and means mounting the disc and the contactmembers for relative rotation. I prefer to use a pair of rotary steppingmtors for producing such relative rotation, one motor being arranged toproduce a predetermined amount of relative rotation in one direction foreach 100 foot increase in altitude and the other motor being arranged toproduce a like amount of relative rotation in the opposite direction foreach 100 foot decrease in altitude. Thus, my encoder is driven in stepsrepresenting foot increments in altitude. Since my encoder is driven infinite steps by such stepping motors, there will be no tendency for itto drift between the levels of altitude at which it is desired that analtitude report be made. That is, my encoder will produce a particularpulse group series steadily until it is stepped in one direction or theother to produce a different pulse group series. I prefer to use rotarystepping motors which produce relatively high output torques so that Ican urge each contact member of the encoder against its associatedcontact strip with greater force which will, in effect, be a load whichmust be overcome by the stepping motors. However, this greater force ofengagement between each contact member and contact strip provides a morereliable contact therebetween.

To the accomplishment of the above and related objects, my invention maybe embodied in the form illustrated in the accompanying drawings,attention being called to the fact, however, that the drawings areillustrative only, and that change may be made in the specificconstruction illustrated and described, so long as the scope of theappended claims is not violated.

in the drawings: FIG. 1 is a block diagram of my altitude indicating andreporting system;

FllG. 2 is a fragmentary elevational view of my encoder;

FIG. 3 is a sectional view taken from H6. 2 generally along the line 3-3and showing the contact strips on one of my encoder discs; and

FIG. 41 is another fragmentary view showing spring means for biasing onedisc of the encoder.

Referring now to FIG. ll, my system, indicated generally by thereference numeral it), will be discussed. The system comprises astandard aircraft altimeter 112 which is equipped with an indicator orpointer Ml arranged for pivotal movement about an axis coinciding withthe axis of the altimeter and means, indicated generally by thereference numeral lit, for tracking the movement of the indicator Ml. Asstated previously, the altimeter 12 may be a conventional altimeterwhich is normally found in the instrument panel of an aircraft. Such analtimeter has a glass cover plate covering and protecting the indicator114i and the scale about which the indicator moves. My tracking meansllii is arranged to track the movement of the indicator M by projectingand reflecting light through this cover plate.

The tracking means 18 is mounted in front of the cover plate of thealtimeter to be in alignment with the pivot axis of the indicator M. Inthe illustrative embodiment, l mount a support plate 22 adjacent thefront face of the altimeter, this support plate carrying a centrallylocated bearing defining a journal axis coinciding with the pivot axisof the indicator M and the axis of the altimeter 112.

The tracking means 18 comprises a shaft 30 journaled in the bearing ofthe support plate 22 and a slip-ring commutator 32 and another supportplate M mounted on the shaft 30 for rotation therewith. The commutator32 may be of conventional commutator construction arranged to provideelectrical connections to rotating bodies.

i have provided a pair of light sources 3%, 40 mounted on the supportplate 34 to direct light through the cover plate of the altimeter towardthe path of movement of the indicator M. A lightresponsive device as, Mis associated with each light source 38, &0, the light-responsivesurface of each device facing the path of movement of the indicator M.The devices d6, M are peripherally spaced apart on the side of thesupport plate (ii which faces the altimeter by an angle which representsa specific altitude increment. For reasons which are clearly explainedin the parent application Ser. No. 739,406 from which this applicationhas been divided, I prefer to make the peripheral spacing between thedevices d6, d8 approximately 72 because altimeters are generallycalibrated so that each 36 increment of movement of the indicator 1dcorresponds to an altitude increment of 100 feet.

Each light-responsive device 46, 48 is arranged electrically to changestate when the amount of light impinging thereon, i.e., impinging on itslight-responsive surface, changes to a predetermined degree. Thus, sinceI project light at the path of movement of the indicator 14, when theindicator moves adjacent to one of the light-responsive devices 46, 48the indicator will reflect light back toward the device to cause it tochange state.

It is necessary, of course, to amplify the outputs of thelightresponsive devices 46, 48 so that these outputs can be used byother electrical equipment. In FIG. 1, it will be seen that I haveprovided such amplifiers for amplifying the output of eachlight-responsive device 46, 48, these amplifiers being indicated by thereference numerals 56, 58. Each amplifier 56, 58 is coupled to andarranged to energize a silicon controlled switch 60, 62 (sometimesreferred to as a silicon controlled rectifier) which is, in turn,connected to and arranged to energize a rotary stepping motor 64, 66.These rotary stepping motors64, 66 comprise a drive means for thesupport plate 34 on which the light sources 38, 40 and thelightresponsive devices 46, 48 are mounted as well as for my encoder. InFIG. 1, as a matter of convenience, I have shown the support plate 34 insolid lines adjacent the face of the altimeter l2 and, again, in dashedlines to illustrate the position of the devices 46, 48 thereon.

The amplifiers 56, 58 and the switches 60, 62 are fully described in theparent application from which this application is divided.

it will be appreciated that, when the indicator 14 moves close to thedevice 46 and reflects light thereon, the motor 64 will be energized todrive the support plate 34 on which the device 46 is mounted about theaxis of the shaft 30. Thus, when the motor 64 is so energized, thedevice is moved away from the indicator and, consequently, the devicestops producing a voltage. When this happens, gate current is withdrawnfrom the gate of the switch 60.

The motor 64 is arranged to drive the support plate 34 in a step-by-stepmanner in one direction about the axis of the shaft 30 and the motor 66is arranged to drive the support plate 34 in a step-by-step manner inthe opposite direction about the axis. Each motor 64, 66 is arranged sothat, each time it is energized, it will drive the support plate 30 anamount equal to one-half the spacing between the devices 46, 48. Thus,once the indicator 14 is between the devices 46, 48, the support plate34 will be driven, in a step-by-step manner to keep the devices 46, 48on opposite sides of the indicator 14. As the indicator 14 approachesone of the devices 46, 48 and reflects light toward that device, thesupport plate 34 will be drivenor jerked to move the device away fromthe indicator. I prefer that the motors 64, 66 be arranged to provide avery fast-action movement of the plate 34 as well as the discs of myencoder. For a description of the rotary stepping motors 64, 66, I referto U.S. Pat. No. 2,496,880 issued Feb. 7, 1950 and US Pat. No. 2,501,950issued Mar. 28, 1 950. I do not, however, intend to be limited to suchmotors because any number of types of solenoid devices can be arrangedto provide a snapaction rotational movement.

In the illustration of FIG. 1, I have arranged the motors 64, 66 todrive a common shaft means 78 which carries a bevel gear 80. The shaft30 is drivingly connected to the shaft means 78 by means of a shaft 86which carries a bevel gear 88 drivingly engaged with the bevel gear 80.The shaft 86 extends through my encoder assembly, indicated generally at90, and constitutes an input shaft means for the encoder assembly. InFIG. 1, the encoder assembly 90 is shown as a box through which theshaft 86 extends. It will be appreciated that FIG. 1 is a diagrammaticalview and that the details of my encoder are shown in FIGS. 2, 3 and 4.It will be appreciated, from FIG. 1, that my encoder 90, which providesthe pulse group output of my system 10, is driven in a step-by-stepmanner by the same means which drives the support plate 34 to track theindicator 14.

The motors 64, 66 and the encoder 90, therefore, constitute a registerfor registering the position of the indicator l4 and providing a pulsegroup series output corresponding to such a position. The amplifiers 56,58 and switches 60, 62, therefore, constitute means for connecting theelectro-optical tracking means 18 to the register, i.e., to the motors64, 66 of the register.

The encoder of the system 10 will provide an output which can becommunicated by a transponder from an aircraft to a ground station. Thatis, each time the support plate 34 is driven to track the indicator 14,the encoder 90 will be driven to provide a pulse group series outputrepresenting the new position of the plate 34 which, in effect,represents the position of the indicator 14. The encoder 90 is,therefore, driven in one direction by one of the motors 64, 66 to addincrements of altitude and driven in the opposite direction by the othermotor to subtract like increments of altitude. In this manner, theencoder 90 registers the position of the indicator 14. In the preferredembodiment, the encoder 90 will add foot increments of altitude as theaircraft climbs and subtract like increments of altitude as the aircraftdescends. Each 36 movement of the support plate 34 represents a 100 footincrement of altitude. It is for this reason that I refer to the encoder90 as a register.

Referring now to FIGS. 2-4, it will be seen that my encoder 90 comprisesa first encoder disc 440 which is mounted on a shaft 442 for rotationtherewith, the shaft being connected directly to the previouslydiscussed shaft 86. Thus, in my preferred embodiment, the disc 440 isdriven in steps of 36 by the rotary stepping motors 64, 66 discussedpreviously. In the embodiment of FIGS. 1 and 2, the disc 440 will bedriven directly with the support plate 34 on which the light-responsivedevices 46, 48 are mounted with one complete revolution of the supportplate 34 and the disc 440 representing an altitude change of 1,000 feet.

The encoder 90 further comprises an encoder disc 444 which is drivinglyconnected to the disc 440 by means of an intermittent motion transfermechanism, indicated generally by the reference numeral 446, and a wormand worm gear means, indicated generally by the reference numeral 448.As illustrated in FIG. 4, l have found that it is desirable to use aspring 445 yieldably to resist rotation of the disc 444 by the mechanism446 and means 448. This spring, which is arranged to permit more thanone revolution of the disc 444 eliminates backlash problems involved inthe mechanism 446 and means 448. The input 450 of the mechanism 446 isconnected to the shaft 442 for rotation with the disc 440. The output452 of the mechanism 446 is mounted for rotation relative to the shaft442 and the mechanism preferably includes means for providing a 5 to Istep reduction between the input 450 and the output 452. The worm 454 ofthe worm and worm gear means 448 is connected to the output 452 forrotation relative to the shaft 442. The worm gear 456 is mounted on theshaft 458 on which the disc 444 is mounted. In one preferred embodimentof my encoder 90, the worm and worm gear means 448 provides a 10 to 1reduction.

Since the disc 440 is driven in steps, the output 452 will be driven onestep each time the disc 440 is driven through five steps in onedirection. The mechanism 446, which preferably is a conventionaltransfer mechanism used in counters, will drive the worm 454 in precisesteps to drive the disc 444 in precise steps. Since there is a 10 to 1reduction provided by the wonn and worm gear means 448, one step of thedisc 444 will be 3.6 which equals an increment of altitude of 500 feet.Thus, a full revolution of the disc 444 represents 50,000 feet ofaltitude.

The aforementioned REPORT No. 8893-SP-l, which specifies the altitudetelemetric code which-my encoder 90 must produce, calls for 9 pulse bitsdesignated as A,, A A B B 8,, D,, D, all for 500 foot altitudeincrements and C C, C all for 100 foot increments of altitude. Thus, myencoder disc 440 provides three concentrically arcuate contact strips460, 462, 464 (FIG. 3). In FIG. 3, I show a contact member C C C,arranged to engage each contact strip 460, 462, 464. Similarly, in H6.2, I have illustrated contact members corresponding to each of the pulseoutputs A,, A A B B B D 1),. While I have illustrated a contact membercorresponding to each of the required pulse outputs, it will beunderstood that l have made no attempt, in FllGS. 2; and 3, to placethese contact members in their proper positions relative to the discs440, 444 with which they are associated. Further, it is within thecapability of those skilled in the encoder arts to arrange contactmembers and contact strips so as to produce desired encoder outputs forgiven positions of the disc. For this particular application, the codeoutput for any given 100 foot increment of altitude is defined in thelCAO agreements.

My encoder 90 is supported on a frame including the horizontallyextending member 466 and the upright members 468, 470 through which theshaft 442 extends. l have illustrated conventional couplings 472, 474for connecting the shafts 86, 30 to opposite ends of the shaft 442.

One advantage of my encoder 90 is that each of the discs 440, 444 isdriven in finite steps by rotary stepping motors. Since, as discussedpreviously, these rotary stepping motors can provide a relatively hightorque output, I can urge the contact members against their respectivediscs 44!), 444 with sufficient force to assure good contact betweeneach contact member and its respective contact strip.

in FIGS. 2 and 3, l have not illustrated the common ground contactmember associated with each disc 440, 444.

What is claimed is:

1. Register means comprising an encoder having an input shaft, a firstrotary stepping motor for driving said shaft in a step-by-step manner inone direction. and a second rotary stepping motor for driving said shaftin a step-by-step manner in the opposite direction, a first discconnected to said shaft for rotation therewith, a plurality ofconcentrically arcuate first contact strips carried by said first discand a stationary contact member engaging each of said first contactstrips, a second disc, a plurality of concentricallly arcuate secondcontact strips carried by said second disc and a stationary contactmember engaging each of said second contact strips, and reducing meansincluding an intermittent motion transfer mechanism providing a drivingconnection between said first and second discs.

2. The means of claim 1 in which said reducing means further includes aworm and mating worm gear, said worm being driven by the output of saidtransfer mechanism and said worm gear being drivingly connected to saidsecond disc.

3. The means of claim ll including spring means operatively connected tosaid second disc and effective yieldably to resist movement thereof bysaid reducing means.

4. The means of claim 2 including spring means operatively connected tosaid second disc and efiective yieldably to resist movement thereof bysaid reducing means.

1. Register means comprising an encoder having an input shaft, a firstrotary stepping motor for driving said shaft in a step-bystep manner inone direction and a second rotary stepping motor for driving said shaftin a step-by-step manner in the opposite direction, a first discconnected to said shaft for rotation therewith, a plurality ofconcentrically arcuate first contact strips carried by said first discand a stationary contact member engaging each of said first contactstrips, a second disc, a plurality of concentrically arcuate secondcontact strips carried by said second disc and a stationary contactmember engaging each of said second contact strips, and reducing meansincluding an intermittent motion transfer mechanism providing a drivingconnection between said first and second discs.
 2. The means of claim 1in which said reducing means further includes a worm and mating wormgear, said worm being driven by the output of said transfer mechanismand said worm gear being drivingly connected to said second disc.
 3. Themeans of claim 1 including spring means operatively connected to saidsecond disc and effective yieldably to resist movement thereof by saidreducing means.
 4. The means of claim 2 including spring meansoperatively connected to said second disc and effective yieldably toresist movement thereof by said reducing means.